Tiny tubes, big pollution

Science News,  Sept 1, 2007  

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A tiny industry has a big problem: pollution. In the first study of its kind, researchers have found that the manufacture of carbon nanotubes produces airborne carcinogens and other pollutants.

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Thousands of times thinner than a human hair, carbon nanotubes are extremely strong and lightweight. A fledgling industry already produces several tons of the tiny tubes each year to strengthen baseball bats, tennis rackets, and sailing masts. Scientists expect future applications to range from biomedical devices to an elevator reaching into space.

Desiree L. Plata, a postdoctoral student at the Massachusetts Institute of Technology and Woods Hole (Mass.) Oceanographic Institute, constructed a benchtop nanotube factory. She injected a carbon compound and a metal catalyst into a container, heated the mixture to 1,000[degrees]C, and collected the output.

Along with each gram of nanotubes, the procedure made 0.6 gram of toxic compounds called polycyclic aromatic hydrocarbons (PAHs). Known carcinogens, PAHs typically waft from burning cigarettes and automobile tailpipes. Plata and her colleagues also detected a second category of pollutants called volatile organic compounds, commonly found in smog.

The team is now working with nanotube manufacturers to help them clean up their act before production skyrockets. "Some factories use [emissions] scrubbers, but most of this stuff just ends up in the air," says Plata. "We're hoping small changes now will prevent big problems in the future."

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